1. Field of the Invention
The present invention relates to a manufacturing method and manufacturing apparatus of printed wiring board and more particularly to a manufacturing method and manufacturing apparatus of printed wiring board which can be preferably used in a package board on which to mount an IC chip.
2. Description of the Related Art
Solder bumps are used to connect the package board and the IC chip electrically. The solder bumps are formed in following processes.    (1) Process for printing solder paste to a connection pad formed in an opening of solder resist layer of the package board    (2) Process for forming the solder bump from solder paste by reflow.
After the solder bumps are formed on the package board, the IC chip is mounted on the solder bumps and by connecting the solder bumps with pads (terminals) of the IC chip by reflow, the IC chip is mounted on the package board.
Currently, the quantity of solder bumps on the package board for CPU is on the order of several thousands. To allow arrangement of a large number of solder bumps, each solder bump has been miniaturized so that its height is reduced and the allowable range of dispersion of the height has been narrowed. For the reason, the solder bump whose height departs from the allowable range needs to be corrected. Upon this correction, a solder bump having a smaller height is melted and removed and then, a solder bump is formed by loading with solder again as disclosed in JP 2003-309139 A and JP 9-64046 A. According to JP 2001-257225 A, whether or not any abnormality exists in the loaded solder ball is detected before reflow and a solder ball having abnormality is replaced before reflow.
However, as indicated in the JP 2003-309139 A and JP 9-64046 A, if the solder bump having a small height is melted and removed, its conductor pad surface is likely to be damaged when the solder bump is removed and when the bump is formed again, connection reliability between the solder bump and conductor pad can drop. On the other hand, because according to the JP 2001-257225 A, the solder ball is replaced before reflow, if the height of the solder bump is short after reflow, this cannot correspond thereto.